EFFECTS OF XYLANASE PRETREATMENT ON THE BLEACHING PROPERTIES OF WHEAT STRAW PULP

This work examines the effects of endo-xylanase and xylosidase pretreatments on the bleaching characteristics of wheat straw pulp. The results show that the brightness of bleached pulp pretreated with endo-xylanase and xylosidase increased by 4.0% and 3.4%, respectively, and that, at a chlorine dosage of 5% (on pulp), the strength of bleached pulps was higher than that of the control. When used together, endo-xylanase and xylosidase act synergistically in the pretreatment of wheat straw pulp prior to bleaching. The brightness of the bleached pulp pretreated with a mixture of endo-xylanase and xylosidase increased respectively by 0.6% and 1.2% greater than that with endo-xylanase and xylosidase solely. However, the bleached Pulp Strength was inferior to that obtained by either endo-xylanase or xylosidase pretreatment. Electron microscopy revealed that the enzymatic pretreatments produced more numerous and larger pores on the surfaces and cross sections of fibers than those existing in untreated pulp.